Single and double spiral chutes for transfer of coal, packages, food products, etc., are known in the prior art. Indeed, the inventor of the present invention, Donald M. Winchester, has received U.S. Pat. Nos. 3,565,226 and 3,566,501 for single spiral chutes, the disclosures of which are incorporated herein by reference. Double spiral chutes for transferring coal and packages are disclosed in U.S. Pat. Nos. 826,613 and 728,626; and in Great Britain Patent No. 970,136.
The present invention is specially designed for the vertical transportation of breakable food products such as potato chips, corn chips, pretzels, and the like. Such food products are susceptible to breakage if they are dropped from one processing station to another. The use of spiral conveyors has been found to be desirable for preventing breakage as such products are transported vertically from one processing station to another.
The present invention is an improvement over the prior art single spiral conveyors of Winchester disclosed in U.S. Pat. Nos. 3,565,226 and 3,566,501. In food processing facilities logistical constraints may dictate that a certain volume of product must be moved vertically from one processing station to another. In some instances the vertical distance between the processing stations is constrained such that a single spiral conveyor will not handle the desired throughput volume. The present invention substantially increases the throughput volume over that of a single spiral conveyor while minimizing product breakage and preventing clogging of the conveyor. The spiral conveyor of the present invention is characterized by a lack of buckling and distortion of the sliding surface and is fabricated without twisting the flat metal sheets used in its construction.
The present invention comprises two spiral chutes beginning in the same horizontal plane, each of the chutes having an inner wall attached to a central tubular support in a helical relationship. A slide attaches along the outer edge of the inner wall and an outer wall is attached along the outer edge of the slide. The double spiral chutes terminate in the same horizontal plane. The double spiral conveyor further includes a positionable discharge pan that receives the product as it is discharged from the two spiral chutes and directs the product as desired.